This invention relates to mixed transition metal catalyst systems comprising late transition metal catalyst compounds and metallocene compounds and polymerization of olefins using them.
Early transition metal catalysts for olefin polymers by coordination polymerization are well-known, typically those are the traditional Ziegler-type catalysts based on Group 4 and 5 of the Periodic Table (IUPAC new notation) and the newer metallocene catalysts based on Group 4-6 metals. However specific late transition metal catalysts suitable for olefin polymerization had not offered the same levels of activity or molecular weight capability for olefin polymerization during the development of these catalyst systems and additional work was published addressing this lack.
In Johnson, Killian, and Brookhart, J. Am. Chem. Soc., 1995, 117, 6414 the reporters describe the use of Ni and Pd complexes for the solution homopolymerization of ethylene, propylene, and 1-hexene. The catalyst precursors are square-planar, M2+, d8, 16 electron complexes incorporating substituted, bidentate diimine ligands. The active coordination sites are occupied by either methyl or bromide ligands. Methyl ligand complexes were activated with H+(OEt2)2[B(3,5-(CF3)2C6H3)4]xe2x88x92 and bromide ligand complexes were activated with methylalumoxane (MAO) or diethylaluminumchloride as cocatalysts.
European patent publication EP-A2-0 454 231 describes Group VIIIb metal catalysts said to be suitable for the polymerization of ethylene, a-olefins, diolefins, functionalized olefins, and alkynes. The described catalyst precursors are Group VIIIb metal (Groups 8, 9, 10, IUPAC new nomenclature) compounds which are subsequently activated by compounds including discrete borate anions. Ethylene homopolymerization in solutions of methylene chloride, toluene and diethyl ether are illustrated.
Since the new late transition metal catalysts exhibit characteristics different from those of transition metal metallocene catalysts or traditional Ziegler-Natta catalysts when used in olefin polymerization, the effects of mixing those catalysts for determining useful benefits are of great interest.
The invention encompasses a mixed transition metal olefin polymerization catalyst system suitable for the polymerization of olefin monomers comprising one late transition metal catalyst system and at least one different catalyst system selected from the group consisting of late transition metal catalyst systems, transition metal metallocene catalyst systems or traditional Ziegler catalyst systems. Preferred embodiments include a mix of at least two late transition metal catalyst system comprising a Group 9, 10, or 11 metal complex stabilized by a bidentate ligand structure, and at least one late transition metal catalyst system, as described, and at least one transition metal metallocene catalyst system comprising a Group 4 metal complex stabilized by at least one ancillary cyclopentadienyl ligand, or at least one late transition metal catalyst system, as described, and at least one Ziegler-Natta catalyst system selected from the group consisting of homogeneous vanadium catalysts and heterogeneous TiCl3/MgCl2 donor catalyst systems. The polymerization process for olefin monomers comprises contacting one or more olefins with these catalyst systems under polymerization conditions.